Sleep is instructive in that the four bodies of Man offer individual insight. In our time, structured by scientific intellectual thought it would be natural to see the human being "turning off", similar to a radio disconnect. The only thoughts as to sleep, scientifically speaking would be an external evaluation via electrodes placed on the skull and the "brain waves" interpreted perhaps during the sleeping and waking state. This is the ongoing thread of scientific materialistic thinking which attempts to "objectify" the human being from without.
The physical, etheric (life), astral and "ego" bodies are immersed within their respective rhythms such that in so far as the etheric body it "holds" the physical body such that if ever let loose totally, death would ensue as the physical body collapses into what is known as a "corpse".
The duty and ongoing work of the etheric body is to "form" and hold to "life" the physical body . The etheric body, known as the formative force body and life body.
The etheric body also speaks to "growth" evident during youth and coming to fulfillment , in our age, at late 20"s. The opposing force which continues on into old age is astral body bound and in true is present from youth as a counterbalance of living activity.
the etheric body does not display "conscious' activity and studying the plant world can clarify these matters. Man in sleep is effectively the configuration of physical and etheric bodies with lack of conscious activity as we know it. The plant also has a physical and etheric body but is denied an earthly consciousness , lacking an astral body, the body of conscious activity.
The plant lives within a "sun rhythm" of spring(growth) , summer(blossom) , fall(degradation) and winter(seed) directly related to solar activity. All plant life, including the evergreen, are within these "sun forces", that same activity morphed from the "Old Sun" evolutionary state.
The human being contains his own particular etheric body and does not follow the solar rhythms though he attempts to sleep at night and remains active during the day . Of course he is able to "sleep" during the day but the most beneficial would be to follow a day/night rhythm of sleep.
One would consider that the human being would have followed a sun rhythm in far away past ages in the forming of his etheric body within the Old Sun state.
At sleep the astral body and "Ego" leave the physical etheric and enter into the spiritual world or that to which we call the spiritual background of "nature". It is not total abandonment but only the loss of astral/ego activity on the nervous system, the seat of earthly conscious activity.
During sleep the human astral body is refreshed or refurbished by higher astral natures such that upon awakening the human being feels "refreshed". The passions, desires and inordinate activity of the astral body , not yet ennobled, are ameliorated in the healing by the higher astral natures.
Of interest are the plants which are considered "poisonous" such that in the case of the belladonna berry it "sucks" cosmic astrality into its berry thus making it poisonous.
https://www.google.com/search?q=bell...hrome&ie=UTF-8
If a plant had a proper astral body it would be formed into an animal nature and of course this is not so within the plant world. The animal does have an astral body in common with but not the same as the human being.
The astral body is poisonous to the human being and the "Ego", even more so. This can clarify " earthly consciousness" as a destructive process whereas the etheric without conscious activity is a constructive force within the human entity.